The inner light-year of the nearest Seyfert 1 nucleus in NGC 4395

The NRAO Very Long Baseline Array (VLBA) was used at 1.4 GHz to image the i nner 550 mas (23 It-yr) of the nearest known Seyfert 1 nucleus, in the Sm g alaxy NGC 4395. One continuum source was detected, with flux density 530 +/ - 130 mu Jy, diameter d < 11 mas (0.46 It-yr), and brightness temperature T -b > 2.0 x 10(6) K. The spectral power P of the VLBA source is intermediate between those of Sagittarius A and Sagittarius A* in the Galactic center. For the VLBA source in NGC 4395, the constraints on T-b, d, and P are consi stent with an origin from a black hole but exclude an origin from a compact starburst or a supernova remnant like Cassiopeia A. Moreover, the spectral powers of NGC 4395 at 1.4 and 4.9 GHz appear to be too low and too constan t to allow analogy with SN 1988Z, a suggested prototype for models of compa ct supernova remnants. The variable and warm X-ray absorber in NGC 4395 has a free-free optical depth much larger than unity at 1.4 GHz and, therefore , cannot fully cover the VLBA source.